The Catholic Church addresses human sexuality within the framework of natural law, emphasizing the intrinsic connection between the unitive and procreative aspects of the conjugal act 1. This understanding is rooted in the belief that God has inscribed certain laws in human nature itself, discoverable through reason and reflection on human experience 2 3.

Here's how the Church addresses human sexuality within natural law:

Integral Vision of Human Sexuality

• Unitive and Procreative Meanings: The Church teaches that human sexuality, particularly within marriage, has both a unitive (love-giving) and procreative (life-giving) dimension 4 1. These two meanings are inseparable and reflect God's design for marriage 5 1.
• Natural Law: According to the Church, natural law dictates that each and every marital act must retain its intrinsic relationship to the procreation of human life 6.
• Moral Implications: Separating these two aspects of the conjugal act is seen as a manipulation and degradation of human sexuality, altering its value of total self-giving 1. Actions that deliberately render procreation impossible are considered intrinsically immoral 1.

The Body's Spousal Dimension

• Expression of the Person: The Church considers the body as an expression of a person’s profound nature 2. Knowledge of human sexuality and the reproductive system helps married couples discover the spousal dimension of the body and its place in God’s design 2.
• Natural Methods: Methods of family planning that are based on an ever-deepening knowledge of the biological rhythms of the human body order sexuality inseparably to the communion of persons and to the gift of life 2.
• Respect for Natural Rhythms: The practice of natural methods contributes to openness and greater sensitivity of each partner towards the other; it is also a training in the ways of interdependence and mutual concern, through respect for the other person’s biological and psychological rhythms 2.

Marriage and Sexual Intimacy

• Reserved to Marriage: Relationships of sexual intimacy are reserved to marriage because only then is the inseparable connection secured between the unitive and the procreative meaning of such matters 5.
• Definitive Communion: Marital acts are ordained to maintain, confirm, and express a definitive communion of life, mediating the realization of a love that is human, total, faithful, and creative 5.
• Moral Disorder: Sexual relations outside the context of marriage constitute a grave disorder because they are reserved to a reality which does not yet exist 5.

Consequences of Separating Unitive and Procreative Aspects

• Distortion of Sexuality: When the unitive and procreative meanings are artificially separated, the original import of human sexuality is distorted and falsified 7.
• Materialistic Perspective: In a materialistic perspective, interpersonal relations are seriously impoverished, harming women, children, the sick or suffering, and the elderly 7.
• Egoism and Abuse: Maintaining both the unitive and procreative significances of human sexuality within marriage defends against slipping into a merely recreational approach to sexuality that generates egoism and often leads to further abuse 8.

In summary, the Church's teaching on human sexuality within natural law emphasizes the importance of maintaining the inseparable connection between the unitive and procreative meanings of the conjugal act, seeing this as essential for upholding the dignity of the human person and the sanctity of marriage.